Black phosphorus is a particular form of the element phosphorus, and has been recognized as having desirable electronic and optoelectronic properties. Black phosphorus can be produced from other forms of phosphorus (such as white phosphorus or red phosphorus) by applying high pressure or high pressure and heat to the phosphorus. A desirable property of black phosphorus (when formed in a thin film) is an electrically tunable band gap around 0.3 eV that is useful as a semiconductor for integrated circuit and photonic applications. Another desirable property is a potentially high mobility (well over 1000 cm2 V−1 s−1) for both electrons and holes in thin films of black phosphorus.
Conventionally, thin black phosphorus has been produced from bulk black phosphorus by exfoliation. The resulting sample size of a thin exfoliated layer is on the order of a few micrometers or tens of micrometers in diameter, and the exfoliation process does not reliably produce uniform layers of black phosphorus. Also, such small sample sizes are not suitable for manufacturing large volumes of microelectronic devices.